you can cast types (like int) to another type (like char).
if you wrote out something like :
char b = 98;
System.out.println(b);
the output will be b, not 98. because java goes hey thats a char 98 isnt a char but 98 is the numerical representation of the char 'b' so lets output that.
say your code is like this. the (char) part explicitly casts the int to a char, and if you dont do that casting this wouldnt compile.
int[] arr = {98, 99, 100, 101, 102, 103};
char one = (char)arr[0];
char two = (char)arr[1];
char three = (char)arr[2];
char four = (char)arr[3];
char five = (char)arr[4];
char six = (char)arr[5];
System.out.print(one);
System.out.print(two);
System.out.print(three);
System.out.print(four);
System.out.print(five);
System.out.print(six);
this would output: bcdefg
so basically they want you to take the input, cast the ints to chars, and print them out. look into explicit and implicit casting of primitives/data types if you need more info.